Resistance welding apparatus

ABSTRACT

Resistance welding apparatus and method for attaching a series of metal pieces to the inside of a metal tube in a predetermined pattern controlled by longitudinal and rotational indexing of the tube. An electrode arm extends into the tube and has an associated feed track along which the metal pieces are intermittently moved to a welding head on the end of the electrode arm. A piston carried by the welding head and acting against the inside of the wall of the tube moves the welding head transversely of the electrode arm to bring the piece to be welded into pressure contact with the inside of the tube. Current is run through the electrode arm, welding head, piece, tube and a grounded contact to weld the piece to the tube.

[45] Patented Aug. 17, 1971 United States Patent 1 3,600,548

[72] Inventor John C. Bock i V 2,550,965 5/195l Brown 219/107 Madison, Wis. 2,556,318 9/l95l Dalin et a]. 219/107 21 Appl. No. 53,530

[22] Filed July 9, 1970 Primary Examiner-J. V. Truhe Assistant Examiner-Hugh D. Jacger Atrorneys- -Joseph G. Werner, Theodore J. Long, John M.

l Assishee Bock Corporation Winter and James A. Kemmeter Madison, Wis.

ABSTRACT: Resistance welding apparatus and method for I 54] RESISTANCE WELDING APPARATUS v I 1 attaching a series of metal pieces to the inside of a metal tube in a predetermined pattern controlled by longitudinal and 4 4 Drawing F rotational indexing of the tube. An electrode arm extends into [1.8. CI the tube and has anassociated feed track along which [he 219/107 metal pieces are intermittently moved to a welding head on [5 l] Int. Cl 823k 9/12 the d f h electrode a m, A iston carried by. the welding [50] Field Search 219/78, h ad a d a ti against the inside of the wall of the tube 7 98, 99 moves the welding head transversely of the electrode arm to bring the piece to be welded into pressure contact with the in- Refinance Cited side of the tube. Current is run through the electrode arm, UNITED STATES PATENTS welding head, piece, tii e and agrounded contact to weld the 3,448,236 6/1969 Spisak 219/98 piece to the tube.

: tubebeing:brokenawaysforzclarity.'

v.andB-with.a,portion of.the bottom-removedfor'clarity.

RESISTANCE WELDING A PARATUS BACKGROUND OF THE INvENTioN The invention relates to a'resistance welding apparatus and method 'forlsecuring pieces within a tubular imemberr while the apparatus and method havebeen developed for welding a spiral pattern of metal baffles on the inside wall of; awheat exchange tube to increase the heat transfer capabilities of the .tube in accordancewith the principles discussed. in 'U..S.L'P,at. Nos. 2,950,740 :and 3,349,754 ,-the.-apparatus and-method baffles and the inside of the-tube during welding. Additionally,

the high amperage electrical current requires-theme of a comparatively large electrode within. the ;.tube which complicates the deliveryandpositioning ofbaffles.in;the-relatively limited working areawithinthetube. p

' SUMMARY OF THE iNvENTioN Basically, the invention comprises .animproved method and apparatus .in a resistancewelding machine for securing :metal pieces within ametalltubeina predetermined vpatternxTl'ie in- .vention'encompasses; the integration of aprimary feed track for .the .pieces' with the electrode v:arm, and .:recip rocating mechanism: for intermittently delivering. asinglerbaffle piece toaweldinghead mountedon the vend .oft-heelectrodeanm for transverse movement withinthe tube.'-.The welding head :hasa positioning pistonv mountedthereon for. engaging; thev inside surface of the tube and-moving the. weldinghead:transversely of the longitudinal .axis 'of: the; -tube-.:to*-.bning. rthe piecer'to -be :welded into high pressure :contact with the-wall of -the.;tube for welding opposite the j positioningpiston. The 1-weld isct'hen made by running aghigh amperage {electrical current through, theelectr'ode; welding head. :piece, tube {and .a grounded .con-

DESCRIPTION oF-A PREFERRED EMBODIMENT AND .METHOD While my improved method and apparatus will be described further herein in conjunction with a welding machine for securing a=series ofbafilepieces in a spiral pattern in a heat exchange-.tubejt should be-.underst ood-that invention is not limited-to that particular use. a

. Referringtthen more. particularly to thedrawings wherein ilike numerals refer to like parts throughoutthe several views, .a resistance welding-machine incorporating my improved apparatus .is .generallys-hown at .10 in Figure 1. Basically the machine has a frame supported, bed :1 l with an indexing screw .12 having a carriage .assembly '13 adapted to be linearly moved .bythe-rotation of -thescrew. The carriage assembly has a motor l4 for rotating atube gripping member 15 which is engaged in one end of the tube :16 in which baffles 17 are to be welded.'-.The gripping member holds the tube in a substantially horizontal cantilevered fashion as shown in FIG. 1. A cantilevered electrode arm .18 if. fixedly mounted at the end of the wrnachine opposite the carriage assembly. The electrode arm is ,aligned'so as to extend intothe tube as shown. The electrode .arm has. awelding head "l9mounted at the end thereof in a slotted guide 19a for. reciprocal transverse movement within the tube for receiving-a piece to be welded and moving that piece into position Iagainstthe inside surface of the tube for welding. The welding head is conductively'connected to the electrode .arm by a flexible conductor element 20.

A ground electrode assembly comprises a contact 21 -.mounted 'onan air cylinder .22 .for reciprocal movement into :and out of contact withthe external surface of the tube The reciprocal contact is conductively connected by a second flex- .ibleconductor element'23 toan electrode arm 24.

An abutment member T25is-=-mounted on the machine bed opposite-the reciprocal grounded contact 21. The abutment member istpositioned in.closelyspaced relationrwith the tube to providea-zstopfor maintaining the tube insubstantial longitudinal alig-nment when contactZl is driven .against the tube.

.head .19; in'their retractedpositions and the tube inslightly FlGS. J .and 2 show thesreciprocal contact 2 1 and welding Spaced relation with the .abutment25 so that the .tube can be tact whichengages theoutside surfaceof'zthe.=tube:opposite .the

piece. I

' The improvement'comprises a simple :and efficient manner of 5 faithfully delivering ;an'cl positioning apieceunderhigh pressure contact with theinside 'wall .of.a:metal tube for:welding thereto.

Further objects, featuressand ;advantages;.of. my invention 'will i be apparent from the-followinglde'tailed descriptionztaken in conjunction with ::the -accompanying..;drawingsa-showinga preferred embodiment iandwmethod.exemplifyingathe::principlesaofmyinvention.

BRIEF DESCRlPTlON OF'THEDRAWINGS FlG. 1 is. a front elevation view generallyshowing. a.-resistance welding ..-machin e -incorporating .-.-my 5 improved app'aratusifor weldingmetalmieces within a.:tube,f aportion of the FIG..Zis-anenIarged'front-elevatiofi viewsofasportion-ofzthe apparatus 'shown in FIG. 1 with '-.the--.welding-=headwin.its .retracted piecereceivingposition. I

f FlGJ. 3..is.anenlargedfrontelevation-view-similar to FIG; .2 I showing .thewelding headimitsextended positionawherein-the piece..=to be .welded .is iheld 1-against:the;:inside surface of .the

tube.

-FlG .'4-isa bottom view=of ithapparatus. shown .in' figuresrZ :indexed,.,that is; moved longitudinally and rotated slightly for weldingzthe next piecein positiom Figure -3..shows thecontact 21in extended position against :the exterior surface of the-tube. The forceof the contact is counteracted by-.theabu.tment2'5 which'is engaged against the tube'opposite the'contact. While the abutment is shown in the rdrawingsas astationarymember against which the tube is moved :by the'force of .the-contact,: it is understood that the 'abutment 'can be.in:the"form.of..a:moveable stop which would movewinto .and out of engagement with the .tube at the same 1 time as :the contact.

"The:cantilevered electrode arm .18 .has a primary feed track ..26-formed-therealong -.to which the pieces or baffles 17 are delivered =by.a chute 27-into which they are manually fed. The pieces:are ,pushed along .theprimaryfeed track insingle file by ithecpistontofan.airzcylinder, a'portion 'of which is shown at 28 irFFlGSJlandA. As each'piece reaches the end of the primary -feed .tracl .26, :an. assembly commonly called a slicer and generallyindicated by numeral 29 displacesthe lead'piece out of .the single .file.line to apositionin'front-ofa secondreciproca'lly acting piston of .an-air oylinder.30. The slicer assembly comprises .a ,pivotally mounted air cylinder 31 operating a pivotal slicer-arm 32-whichengages the lead piece through an openingjBSzin aguidezplate34. When-thepiston 28-has moved i.thedeadEpiecetoltherendofxthe primaryfeed track'26 opposite athe slicer.arm.3.2, air cylinder 31 is actuated to pivot the slicer iarm formovingthe lead-piece out of the primary feed trackto aposition'adjacent-the-end of thepiston of air cylinder30 as showniin'FlGA. Aircylinderi30 is then actuated to extend the apiston.thereofand pu'sh'thepiece. along a secondary feed track .535-to-the-end .of-{thewelding head 19..The* grounded contact '21 isthen extended by air cylinder 22 which moves the tube slightly into engagement with the abutment 25 as shown in FIG. 3. A hydraulic positioning piston 36 then drives the weldcontact with the inside surface of the tube 16. A sufficiently 'high amperage electrical current is then run through the elecnode 18 and its associated flexible conductor element 20, welding head 19, baffle piece 17, tube 16, contact'2l and its associated flexible conductor element 23, and electrode 'arm 24 to complete the weld. A i

In order to achieve the aforementioned spiral pattern, the tube is moved to a new position after each baffle piece is welded. The first weld is made with the tube as far onto the cantilevered electrode arm 18 as may be desired for the beginning of the baffles. After each baffle piece is welded, the tube is then rotated slightly by rotation of gripping member and backed-off the electrode arm by indexing screw 12.-This rotational and longitudinal movement of the tube is preferably carried on at the same time that the baffle pieces are moved along the primary feed track of the electrode arm and the lead baffle piece moved into position on the welding head. The

cycle is repeated -until the desired number of baffles have been welded in the tube. The tube is then removed from the machine by loosening gripping member 15 and another tube positioned thereon and readied for welding.

It is understood that the present invention is not confined to the particular steps, construction or arrangement of parts herein illustrated and described for exemplification, but embraces all such modified forms thereof as come within the scope of the following claims.

lclaim:

1. In a resistance welding machine for welding metal pieces 'ing head 19 fromits retracted piece receiving position shown armeans for holding the tube in which the pieces are to be welded, Y

b. a primary feed track for delivery of a pieces in single file line into said tube,

c. a welding head mounted at the end of 'said'primary feed track for movement transversely of the longitudinal axis ofthe tubejbetween a retracted piece receiving position and a transversely extendedwelding position, said welding head having a secondary feed track positioned to receive the lead piece from said primary feed track when said welding head is in said retracted piece receiving position, g

d. means for moving said lead piece along the secondary feed track to the end thereof,

e. positioning means attached to said welding head for moving said welding head from said piece-receiving position to said welding position to maintain the piece on said welding head in pressure contact with the inside surface of said tube, and

means for running an electrical current through the piece on said welding head and theitube to weld said piece to said tube.

2. The improvement as specified in claim 1 comprising a cantilevered electrode substantially aligned with the tube holding means for extending into a tube secured by said tube holding means, said primary feed track extending along said cantilevered electrode, and means for intermittently advancing said pieces along said primary feed track.

3. The improvement as specified in claim 1 wherein said tube holding means has indexing means associated therewith plurality of the for rotating and linearly moving said tube.

4. The improvement as specified in claim 1 wherein said positioning means comprises a piston on said weldin g head for engaging against the inside surface of said tube to move said welding from said piece receiving position to said welding position. 

1. In a resistance welding machine for welding metal pieces to the inside surface of a metal tube, the improvement comprising: a. means for holding the tube in which the pieces are to be welded, b. a primary feed track for delivery of a plurality of the pieces in single file line into said tube, c. a welding head mounted at the end of said primary feed track for movement transversely of the longitudinal axis of the tube between a retracted piece receiving position and a transversely extended welding position, said welding head having a secondary feed track positioned to receive the lead piece from said primary feed track when said welding head is in said retracted piece receiving position, d. means for moving said lead piece along the secondary feed track to the end thereof, e. positioning means attached to said welding head for moving said welding head from said piece receiving position to said welding position to maintain the piece on said welding head in pressure contact with the inside surface of said tube, and f. means for running an electrical current through the piece on said welding head and the tube to weld said piece to said tube.
 2. The improvement as specified in claim 1 comprising a cantilevered electrode substantially aligned with the tube holding means for extending into a tube secured by said tube holdinG means, said primary feed track extending along said cantilevered electrode, and means for intermittently advancing said pieces along said primary feed track.
 3. The improvement as specified in claim 1 wherein said tube holding means has indexing means associated therewith for rotating and linearly moving said tube.
 4. The improvement as specified in claim 1 wherein said positioning means comprises a piston on said welding head for engaging against the inside surface of said tube to move said welding from said piece receiving position to said welding position.
 2. The improvement as specified in claim 1 comprising a cantilevered electrode substantially aligned with the tube holding means for extending into a tube secured by said tube holdinG means, said primary feed track extending along said cantilevered electrode, and means for intermittently advancing said pieces along said primary feed track.
 3. The improvement as specified in claim 1 wherein said tube holding means has indexing means associated therewith for rotating and linearly moving said tube.
 4. The improvement as specified in claim 1 wherein said positioning means comprises a piston on said welding head for engaging against the inside surface of said tube to move said welding from said piece receiving position to said welding position. 